Insert order detail in laravel

Good evening I'm working with laravel 5.4 the problem is that I have two tables an order and detail of order I made a shopping cart is all good with session to what I'm going is that when I want to insert the order table and order detail does not insert. I leave the code there, Any contribution is welcome thanks in advance. PS: I'm with mysql

this is the driver:

public function postgrabardetalle(Request $request)
{



    try {
            DB::beginTransaction();
            $pedido=new Pedido;
            $pedido->cod_cliente=$request->get('cod_cliente');
            $mytime=Carbon::now('America/Lima');
            $pedido->fecha=$mytime->todateTimeString();
            $pedido->igv='18';

            $pedido->cod_empleado=1;
            $pedido->estado='1'; 
            $pedido->save();

            $detpedido=new DetallePedido;


            $cod_producto=$request->input('cod_producto');
            $cantidad=$request->input('cantidad');
            $precioventa=$request->input('precioventa');
            $importe=$request->input('importe');

            //$cart=new Carro($oldCart);
           $contador=0;
           while ($contador < count($cod_producto)) {            
                $detpedido->cod_pedido=$pedido->cod_pedido;
                $detpedido->cod_producto=$cod_producto[$contador];
                $detpedido->cantidad=$cantidad[$contador];
                $detpedido->precioventa=$precioventa[$contador];
                $detpedido->importe=$importe[$contador];                
                $detpedido->save();
                $contador=$contador+1;
            }

            DB::commit();

        } catch (Exception $e) {
            DB::rollback();
        }
        Session::forget('carro');
     return Redirect::to('/carro')->with('success','pedido agregado correctamente');  
     //return $cod_producto;  


}

this is the view

-----------------------------------
@extends('layouts.inicio')

@section('content')

  @if(Session::has('carro'))
<form action="{{route('grabardetalle')}}" method="POST">
    <div class="row">
      <div class="col-sm-6 col-md-6 col-md-offset-1 col-sm-offset-1">
        <label for="cliente">Clientes</label>
        <select name="cod_cliente" id="" class="form-control selectpicker" data-Live-search="true">
          @foreach($clientes as $cli)
          <option value="{{$cli->cod_cliente}}">{{$cli->nombre}}</option>
          @endforeach
        </select>
      </div>
      <div class="col-sm-6 col-md-6 col-md-offset-1 col-sm-offset-1">
        <h3 class="col-sm-offset-4">Detalle de Pedido</h3>
        <br>
        <table class="table table-striped table-hover table-bordered">
          <thead>
            <tr>
              <th class="info">Descripcion</th>
              <th class="info">Cantidad</th>
              <th class="info">Precio</th>
              <th class="info">Importe</th>
              <th class="info">Acciones</th>

            </tr>
          </thead>
          <tbody>
            @foreach((array)$producto as $pro)

            <tr >
              <td style=""><input type="hidden" name="cod_producto[]" value="{{$pro['item']['cod_producto']}}"  disabled=""> {{$pro['item']['descripcion']}} </td>
              <td> <input type="text" name="cantidad[]" value="{{$pro['cant']}}" disabled="" > </td>
              <td><input type="text" name="precioventa[]" value="{{$pro['precioventa']}}" disabled="" > </td>
              <td><input type="text" name="importe[]" value="{{$pro['importe']}}" disabled=""> </td>

              <td width="50"  ><a href="{{ route('carro.reducituno', ['id' => $pro['item']['cod_producto']])}}"  type="button" class="btn btn-danger">Elimnar 1</a>
                         <a href="{{ route('carro.removeItem', ['id' => $pro['item']['cod_producto']])}}" type="button" class="btn btn-primary">Limpiar</a></td>
            </tr>
            @endforeach
          </tbody>
        </table>
      </div>
    </div>
    <div class="row">
      <div class="col-sm-6 col-md-6 col-md-offset-1 col-sm-offset-1">
        <h3>Total: S/. <input type="text" name="" value="{{$subtotal}}"  disabled=""> </h3> 
      </div>
    </div>
    <hr>
    <div class="row">
      <div class="col-sm-6 col-md-6 col-md-offset-3 col-sm-offset-3">
        {{ csrf_field() }}
        <button type="submit" class="btn btn-success" name="">Grabar</button>
         <button type="reset" class="btn btn-danger" name="">Cancelar</button>
      </div>
    </div>
    </form>
  @else
  <div class="row">
    <div class="col-sm-6 col-md-6 col-md-offset-3 col-sm-offset-3">
      <h2>No Hay Productos Agregados</h2>
    </div>
  </div>
  @endif

@endsection